If you are using Exchange Online and have enabled journaling, you will be able to exclude voicemail and missed call notification from being journaled.

This capability will be rolled out in early November but if you are using journaling and want to exclude such notifications you can already run the below PowerShell command using Exchange Online PowerShell module

To disable journaling

Set-TransportConfig -VoicemailJournalingEnabled $false

To (re) enable journaling

Set-TransportConfig -VoicemailJournalingEnabled $true

You can check if you have enabled/disabled this capability, you can use the command

Get-TransportConfig | fl VoicemailJournalingEnabled